Locking device for electric lamps.



H. T. WORRALL.

LOCKING DEVICE FOR ELECTRIC LAMPS.

' APPLICATION men DEC.26, 1913.

Patented Apr. 2?, 1915,

"an scares raisin canes HENRY TOWNSEND WORRAIJ OF CHELMSFORD, ENG-LAND.

LUCKIhlG-DEVICE FOB ELECTRIC LAMPS,

To all whom it may concern Be it known that I, HENRY TOWNSEND NORRALL, a subject of His Majesty the Kin of England, residing at 202 Springfiel road, Chelmsford, inpthe county of Essex, Kingdom of tails anypecuniary loss, inconvenience and annoyance caused through lamps being stolen or wrongfully removed by unauthon iced persons. In large establishments serious and unsuspected losses are often incurred from the above mentioned cause;

The principle I adopt while retaining most of the Well known features of the bayonet type lamp ofother fitting, makes a slight increase as regards dimensions absolutely necessary but this increase is of no importance whatever. seeing that in most of the modern metal filament lamps the bulbs have enormously increased in size While the lamp sockets have consistentlyremained the same, the bulb and the socket as at present constituted being greatly out ofproportion "to each other.

The invention is hereinafter described with reference to the accompanying drawings in which Figure 1 is an elevation of the porcelain insulator of the lamp holder or socket showing the docking shaft fitted thereto; and Figs. 2 and 3 are a top and an underneath plan view, respectively of said insulator.

Fig. 4 is a plan of the top section of the two-partlamp cap; and Fig. 5 is an elevation of same. Fig. 6' is an elevation of the bottomsection of the lamp cap. Fig. 7 is an elevation showin 'the two sections of the lamp cap"assemblco. Figs. 8 and 9 are views of one of the fastening staples. Fig. 10 is a sectional elevation of thezcoinplete device.

Putting my invention into practice I fix a concentric locking shaft a to the porcelain insulator b of the lamp-holder or socket, which locking shaft is self-centering. self- Speeiflcation of Letters Patent.

England, have invented a cer-' tain new and useful Locking Device for usual manner.

alining and entirely insulated from the plunger contacts 0. It is composed preferably of'llexible metal, is cross slotted at d to form three, four or any number of concentric locking jaws e, and is madeto fit loosely in a suitable hole f provided in the center of the porcelain insulator b and to- :bear on a shoulder g. A collar 71. is fitted ends and formed with an external rib 7c projecting at a point about half its length, which rib prevents any displacement of the cylinder in the insulation Z of the section 3, of the cap.

. T.1G lamp cap is composed of two distinct parts or sections namely theupp-er section Z and the lower section m, adapted to be detached one from'theother. The upper section Z carries, in addition to the locking cylinder j, contacts which may be of the ordinary type. K prefer, howeveigto use the pattern shown at n asbeing the more suit able for this particular device. It will be noticed, by reference to Figs. 4, 5 and. '7, that the usual radial lamp attaching pins on the upper section of'the cap are dispensed. with. instead of such pins, Which are ai vvays liable to become loose, to break or on". I bring into use one or more co. indents 0, andthese indents, as will be easily understood, slide Within corresponding in- 4 dents in the lamp-holder. However, l have.

found that oneindent only, if Well made, is quite sufficient to prevent the lamp being twisted around when "locked in they holder, and of course the usual pins and slots may take the place of indents if preferred.

The lower section m of the cap carries the lamp bulb m to which it is cemented in the Both sections Z and m are spun, pressed .or formed with extension pieces 70 of slightly difl'erent diameters, and the extension piece of the section Z is of such diameter as to permit of a good sliding fit being made on the extension piece of the section m thus forming a telescopic like junction as in Fig. 7. For the purpose of attaching the two sections together two or more small holes g are punched through the Patented Apr. 23?, 1915. Application filed December 526, 2.913. Serial Ho. 808,763.

said junction equidistant a art, and suitable fasteners or staples r, ashioned as in Fig. 8, are'inserted in the holes and then pressed fiat as in Fig. 9. The upper and lower sections now become securely united an form a complete cap as in Fig. 7. If

one or the other of the cap sections Z and m was twisted radially, i. 2., one independently of the other, undue lateral strain would fall on the soft metal fasteners r, and these in turn would have a tendency'to straighten and bent, to shape as in Fig. 8 and are made of soft sheet brass of about the same gage as the capsections, and although made of such slender .metal they are amply strong enough when fixed to withstand any pressure brought to [march them edgewise.

Fig. 7; shows an exterior view of a complete "cap ready to have'a bulb cemented thereto. To put a new lamp in the lamp-holder, as

suming the, lamp and the lampholder arefitted with the parts 'now fully described, all

that is required is a straight push intothe holder and this causes the insulated concentric locking shaft we the holder to travel the entire len' th-of thejinsulat'ed locking cylinder 7' in t e lamp cap, resulting in an insulating automatic lock being made in the inters ace of the lamp cap as shown in Fig. 10. houldany attempt now be made to remove the lamp m, locked in the manner aforesaid, from the holder it will be rendered practically useless for all intents and purposes as described hereafter.

When a defective lamp requires removal the soft metal fasteners or staples r are withdrawn from the sectional lamp cap Z" and m. This leaves the section m of the cap 'free to be detached from the section Z by a slight downward pull, the said pull reaking the current conductors m inside the lamp gap The current conductors m are construted so that they have their weakest breaking points situated near to the plunger con: tacts 0 and this arrangement prevents any possibility of a short circuit taking place during the said process of extraction. The

lower section m of the cap being now removed the upper section Z may-be unlocked by pressing together the jaws e of "the insulated locking shaft-c and the plunger contacts c of the lamp-holder, being in a state of depression, will eject the section Z of the cap from the holder. The holder is now ready to receivezja-new'lamp. No tool, key or switch is requirediand the locking shaft a, being perfectly insulated from the live plunger contacts 0, may be handled by the for engagement with said plug contacts and locking cylinder respectively, said locking means being capable of being released only upon separation of said-upper and lower members, substantially as described.

2. In' a device, of, the class; described, a

lamp provided with-a cap-formed of upper s and lower detachably" connected sections, said upper section" having a plug provided with a central opening andelectrical contacts, a pair of conductors connecting to saidcontacts and passing through said lower section to said lamp; in combination with a socket provided with electrical contacts and an outwardly extending centrally disposed locking shaft for engagement with said plug contacts, and said opening respectively, the said locking shaftbeing capable of being-re leased only upon separation, of said upper and lower. members, and the sides of said cap and socket being provided with 'cooper- 1 ating indentsifor properly alining said contacts and preventing rotation of said lamp and socket, substantially as described.

3. In a, device of the class described,lthe' combination of a lamp and socket,'said lamp being providedwith a cap formed of upper and ower detachable sections, said upper section havin a plug provided with contacts and a centra ly .dispo sed locking cylinder communicating with said lower section,'the filaments of said lamp extending through said lower section and connected to said contacts, said socket being provided with contacts and a'noutwardly extendin shaft, said shaft bein adapted to be-exten ed through said cylinder and having spring shoulders at its outer end for snapping engagement behind said Plug,; and means'for securing said upper and lower sectins together, substantially as described.

4. In a device of the class described, thecombination of a lamp and a socket, said lamp being provided with acap comprisin upper an ower separable sections, sai

upper section having a plug provided with contacts, current conductors, connected to said contacts and passing within said lower section to said lamp, means for securing said upper and lower sections together, contacts on said socket for en agement with the contacts on said plug w on the said cap is inserted within said socket, and coii crating means within said socket and lamp orholding the same together, the said means being accessible for releasing the socket and lamp only upon separation of said upper and lower members, substantially as described.

5. In a device of the class described, a lamp and a socket, said lamp having the usual current conductors and bein provided with a cap adapted to fit within said socket, said ca comprising a pair of inter locking separa le sections, one of said sections being provided with a centrally disposed locking cylinder and also a pair of contacts'to which the ends of said current conductors are secured, and the other of said sections being secured at one end to said lamp and supporting said first named sec- 'tion at its opposite end spaced from said vided with a plug having contacts, said upper and lower sections having interfitting flanges provided with registering openings, locking members for coiiperation with said openings for holding said sections assembled, the filament of said lamp extending through said lower section and secured to said contacts, whereby upon separation of said members the said filament will be broken, and said plug being provided with an openin extending therethrough toreceive a 100 ing device, substantially as described.

'7. In a device of the class described, a

vided with a centrally disposed outwardly extending locking shaft, said lamp having a cap comprising upper and lower sections, said upper section being provided with a plug having contacts and a centrally disposed locking cylinder communicating with said lower section for the reception of said locking shaft, said upper and lower sections having interfitting flanges provided with registering openings, locking members for cooperation with said openings for holdin said sections assembled, the filament of sai lamp extending through said lower section to be secured to said contacts, wheieby upon separation of said sections the said filament will be broken and cooperating locking means upon said locking shaft and said locking cylinder releasable only upon separation of said upper and lower members, substantially as described.

In testimony whereof I have signedthis specification in the presence of two subscribing witnesses.

HENRY TOWNSEND WORRALL. Witnesses J. S. Amman, FRANK BLAKEY. 

